Re: git segfaults on older Solaris releases

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 7, 2016, 18:50 UTC
Message-ID: <xmqqk2k9z20p.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <xmqqoa9lz2uw.fsf@gitster.mtv.corp.google.com>

Junio C Hamano <gitster@pobox.com> writes:

Show 13 quoted lines

> "Tom G. Christensen" <tgc@jupiterrise.com> writes:
>
>> The reason for the crash is simple, a null value was passed to the 's'
>> format for the *printf family of functions.
>> ...
>> Passing a null value to the 's' format is explicitly documented as
>> giving undefined results on Solaris, even on Solaris 11(2).
>
> Do you mean
>
> 	*printf("...%.*s...", ..., 0, NULL, ...)
>
> i.e. you saw a NULL passed only when we use %.*s with width=0?

So, I've looked at places where we use "%.*s" with "prefix" nearby, and it seems that this is the only place.

The "prefix" being a NULL is a perfectly valid state throughout the system and means a different thing than it being an empty string, so it is valid for callers of prefix_path() and prefix_path_gently() to pass prefix=NULL as long as they pass len=0.

So perhaps this is all we need to fix your box.

 setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.c b/setup.c
index 3439ec6..b6c8aab 100644
--- a/setup.c
+++ b/setup.c
@@ -103,7 +103,7 @@ char *prefix_path_gently(const char *prefix, int len,
 			return NULL;
 		}
 	} else {
-		sanitized = xstrfmt("%.*s%s", len, prefix, path);
+		sanitized = xstrfmt("%.*s%s", len, prefix ? prefix : "", path);
 		if (remaining_prefix)
 			*remaining_prefix = len;
 		if (normalize_path_copy_len(sanitized, sanitized, remaining_prefix)) {